In the US Chess League quarterfinals, teams battled it out
to advance to the next stage of the playoffs, fighting to be crowned the 2012
League Champions. The results in the two divisions were in reverse, with both
favored teams winning in the East, while the West saw some incredible upsets.
Here is the action, match by match:Eastern DivisionPhiladelphia Inventors - Baltimore Kingfishers 3.5-0.5

This match was definitely closer than the score suggests,
perhaps since some of Baltimore's playersplayed too aggressively in order to overcome the draw odds. That said,
Philadelphia proved themselves to be the stronger team, with FM Tom Bartell
beating GM Larry Kaufman and IM Richard Costiganwinning over FM Ralph Zimmer. I'd like to show
an instructive chunk from the top board:

GM Sergey Erenburg (PHI) - IM Tegshsuren Enkhbat (BAL)
1-0

This
position is quite complex, as Black has more space in the center, while White
has some annoying pressure on the kingside. Nxf6?? is met with Nxf6 trapping
White's queen, and Nxh6+ would also be careless due to Bxh6 Qxh6 Rh8 Qxg5 Nh4!
And if White takes the knight Rg6 wins the queen, but otherwise after Nf3+
Black gets a devastating attack against White's king, using the newly opened g-
and h- files. Instead, GM Erenburg finds a strong idea with 29.Nc5! Nxc5 (The
knight must be captured, as 29...Qc7 simply loses to 30.Nxd7 Qxd7 31.Nxf6+-) 30.dxc5
Qxc5 31.Be3!

A
good practical decision by Erenburg! (Grabbing the exchange is always tempting,
but after 31.Nxf6 Bxf6 32.Be3 (32.Qxh6?? Rh8-+) 32...Qd6 A human would
normally evaluate this position as clearly better for White, but with practical
chances for Black, especially if the knight lands on either the d3 or f3
squares. However, concretely White has the powerful break 33.f4!± Opening lines
against Black's king, and Black is in serious trouble. Without seeing this
break, though, one can see the difficulties in converting the full point.) 31...Qd6
32.Bd4 This is the point, instead of winning the exchange, White wins both
of Black's kingside pawns. 32...Rfe6 33.Bxg7 Kxg7 34.Qxh6+ Kg8 35.Qxg5±
Now
White has a clear advantage, due to the extra pawn, as well as holding the
initiative for the rest of the game, due to the vulnerability of Black's king.
The practical considerations of this position make me think this was a better
choice than winning the exchange outright, and is fairly instructive for
materialistic players. Erenburg went on to gradually build his advantage and
win a fairly clean game. 1-0

Manhattan Applesauce vs. New York Knights

In this match one could clearly see the practical problems
when playing against draw odds. At one point it seemed like both GM Tamaz
Gelashvili and NM Alexander Katz were playing for a win simply because they had
to, and not because their position dictated it. After taking on too much risk
they both ended up losing. Ironically, the other two boards ended up in New
York's favor, with SM Matt Herman winning a crazy game (crazy is putting it
mildly) over IM Eli Vovsha, while FM Michael Bodek ended up holding a draw in a
worse endgame against NM Andrew Shvartsman. Thus had Gelashvili and Katz drew
their games New York would have won the match, but alas hindsight is 20/20.

Herman's win ended up being the Game of the Week:

Western Quarterfinals

Dallas Destiny vs. Seattle Sluggers 1.5-2.5

A tough match for Dallas, who were heavily outrated on board
four, and needed to score 2/3 on the top three boards to advance. They only
managed 1.5 points, although not in the way that one would have expected. GM
Julio Sadorra managed to beat GM Varuzhan Akobian, who was 3/3 in the season,
while GM Conrad Holt, a large favorite over IM Georgi Orlov, lost the thread in
a complex position and ended up being on the wrong side of a Game of the Week
runner-up.

NM Artur Safin was unable to break NM Joshua Sinanan's defence, and
was even losing at one point, although ultimately the game ended in a draw.
This result, along with wins by IM Orlov and NM Lessler clinched the match for
Seattle.

Here is the decisive excerpt from Sadorra-Akobian:

16.Qa4!
GM Sadorra justifies a risky pawn grab with this strong move. 16...Qd7 Akobian
spent about half an hour here, perhaps realizing that White was going to be
better in all lines and tried to find a way to minimize the damage. (16...Nb4
17.Rxc5 bxc5 18.a3! and the knight is trapped.; 16...Nb8 17.Rxc5 bxc5 18.Ne5 is
clearly better for White, who will likely win the d5-pawn soon.) 17.Ne5 Rxe5
18.fxe5 Nb4 (18...Nb8 creates back rank problems for Black and loses to
19.Bxd5 Qxd5 20.Rc8+ Bf8 21.Qe8+-) 19.d4!

Deflecting
the bishop away from the c-file, saving the rook. 19...Bf8 20.Rfc1 Rc8 (20...Nxc6
21.Qxc6 Qxc6 22.Rxc6+- Black will lose either the d5-pawn or one of the
queenside pawns, and the endgame is more or less hopeless.) 21.Bh3!+-

I'm
guessing that Akobian had missed this move in his previous calculations of Qd7,
as Black is holding in all other lines. Unfortunately for Black, this
"only move" allows White to win a decisive amount of material, and
the game was over pretty soon afterward. 1-0

Arizona Scorpions - Saint Louis Arch Bishops 2.5-1.5

Perhaps the most surprising result of the week, since going
into this match the Arch Bishops had won five of their last six matches
(interestingly the one loss was to Arizona). This streak was mostly thanks to the
efforts of IM Priyadharshan Kannappan and IM Levan Bregadze, Kannappan being
the landslide winner of the 2012 MVP award, while Bregadze came in third in the
contest. However they both lost in this match, to Arizona's IM Levon Altounian
and IM Shahin Mohandesi.

Kannapan was doing fine until Altounian found 48...Ra5!
Forcing White to exchange queens, leading to a lost endgame for the 2012 MVP.

A draw on the top board , IM Mackenzie Molner - GM Andre
Diamant, sealed the match for Arizona.